The reliability offlip-chip-interconnects is primarily affected by the thermo-mechanical deformation ofthe solder ball or bump, which is a consequence ofthe well-known CTE-mismatch problem. The common approach to determine the stresses and strainsfor reliability predictions in the critical interconnections is the use offinite elements simulations ofthe assembly. Simulation results should be verified by experiments in order to prevent systematic errors. A combination oftests and FE-simulations can help to reduce the simulation errors and to verify the computed results. The objective ofthis work is to apply modern test methods for thermo-mechanical investigations on CSP-andflip-chip-assemblies and to evaluate these quantitatively and qualitatively. Applied test methods were electronic-speckle-pattern-interferometry (ESPI)